It's very plausible to disagree with some of their choices. For instance, you might be interested in efficient charitable giving within your country, and bite the bullet of "this means I value starving africans a lot less." The important part is to prompt charities to document costs and outcomes in general (preferably to a scientific standard), so that people can make more informed choices about their donations no matter their values.

If an organization cures blindness for $20 through cataract surgeries in developing nations, and another spends $40,000 to train a seeing eye dog for a single individual, we are looking at ratios of 1:1000 in terms of effectiveness. The amount spent on 'overhead' is irrelevant!